1. Field of the Invention
This invention relates to computer terminal apparatus, and more particularly to the factory data collection terminal.
2. Description of the Prior Art
Factory data collection terminals are generally installed in factory areas for use of personnel to enter information pertaining to the operation of the factory. For example, they may be placed in unattended areas in the factory for use of production workers in recording the starting or stopping of a job. They can be utilized for inventory control, or provide the database for payroll calculations. Generally the areas in which such factory data collection terminals are located are quite dirty as compared to office areas, banking operations, and other similar type of commercial operations. Accordingly such data collection terminals are enclosed in dustproof packages.
A typical prior art unit is shown on FIG. 1. A dustproof enclosure 101 protects the internal mechanism from dirt, dust, grease and other harmful contaminants in the atmosphere. The unit is designed to be mounted against a wall or post via mounting brackets 103. Information may be entered into the unit via keyboard switches 102 or via card reader slot 106. Power, data signals and address signals are provided to the unit via a conduit 104 encasing wires 105, as shown in the cut-away of FIG. 1. Many such units may be placed at various locations in the factory. They are all interconnected, generally into a main computer system which is remotely located. Each unit can provide information for storage or processing by the computer system. In order to identify the source of information, each factory data collection unit has an address by which it is identified. Each data collection unit also has its own baud rate for transmitting information to the central processing system or receiving information from it. The baud rate of one unit may be different from another unit. A problem arises when maintenance is required of any of these data collection units. By removing the enclosure 101 in order to diagnose and correct a problem, the internal mechanism is exposed to contaminants and untrained maintenance personnel which can cause other more severe problems. Accordingly, it is desirable to remove the entire factory data collection unit without exposing any of the internal mechanism and replace it with another operable unit. The inoperable unit would then be sent to a central maintenance depot, repaired and returned. Under the prior art arrangements, it was not possible to remove the entire unit without in some manner exposing the internal mechanism to the factory contaminants.
What was required was a special enclosure housing all the various connecting circuits which could be removably attached to the factory data collection terminal, and which could be opened to the factory atmosphere to permit the removal of the data collection sealed terminal. After removal of the inoperable data collection terminal, what was further required was to have it replaced with an operable one until the original data terminal was repaired at a centrally located maintenance depot and returned, again without exposing the internal operating mechanisms of the data terminal. What was further required was to retain the same identification address for the special connector as the inoperable terminal. Since each data collection terminal has its own identification address, it was necessary to have the address of the replacement unit disabled via means located in the connector and to set the address of the disabled terminal again by means located in the connector so that any other unit in the system addressing the new terminal utilizing the old address would be able to communicate with the new terminal as if it were the old terminal.
Another problem in replacing an inoperable terminal with an operable one was that the baud rate of sending signals may be different than for the terminal replaced. Accordingly, another requirement of an improved connector was a means in the connector for selecting different baud rates.